Azo dyestuffs



Patented Dec. 21, 1937 UNITED STATES PATENT OFFICE 2,102,593 AZO DYESTUFFS Johann Heinrich Helberger, Gologne-Mulheim,

and Otto Bayer, Leverkusen-I. G. Werk, Germany, assignors to General Aniline Works, Inc., "New York, N. Y., a corporation of Delaware No Drawing. Application November 18, 1935, Serial No. 50,470. In Germany November 23,

3 Claims.

The present invention relates to new azodyestuffs, more particularly it relates to azodyestuifs which may'berepresented by the general formula: v

wherein X stands for hydrogen or alkyl which may bear substituents, and R stands for the radical .of adiazotized aromatic diazotizationvcomponent, such as a radical of the benzene or naphthalene series. V

Our new dyestuffs are obtainable by coupling in an acid medium py-tetrahydro-'7-hydroxynaphthopyridine of the formula:

wherein X means the same as stated above, with aromatic diazo compounds.

Dyestuffs of especial technical interest are obtained when using diazotization components of group, an alkyl group an alkoxy group, the hydroxy group, and halogen. The cellulose acetate dyestuffs thus'obtained generally yield clear blue (01. zoo-38.5)

to green shades of good fastness to light and of v very good dischargeability.

Compared with similarly constituted dyestuffs those obtained in accordance with the present invention are distinguished by their clarity and by their shades, which are distinctly turned to the blue to green part of the spectrum, and itis remarkable that with the aid of certain bases, such as with p-nitranilines, dinitranilines and the like,

there are obtainable shades which have been un-' known up to the present in the series of monoazodyestuifs for acetate artificial silk. The new dyestuffs are technically valuable due to the clarity of their shades combined with the very good fastness to light and excellent dischargeability, and they fulfill a long felt want in the field of dischargeable dyestuffs for cellulose acetate.

The invention is illustrated by the following examples, but not restricted thereto:

Example 1 13.8 parts by weight of p-nitraniline are diazotized in the usual manner in aqueous hydrochloric acid with 6.9 parts by weight of sodium nitrite which have been dissolved in hot water.

The diazo solution is, then introduced into an aqueous mineral acid solution of 23.3 parts by weight of py-tetrahydro-7-hydroxynaphthopyridine hydrochloride; the coupling commences im- The dyestuif having the following formula:

N H EH:

is isolated in the usual manner. It dyes acetate silk from a soap bath greenish-blue shades of good fastness to light and good dischargeability.

The py-tetrahydro-7-hydroxynaphthopyridine can be prepared in the following manner:

50 parts by weight of the sodium salt of -naphthopyridine-7-sulfonic acid (obtainable by reacting upon 1-naphthylamino-5-sulfonic acid with V mediately and is complete after a short time. V

V glycerin, nitrobenzeneand sulfuric acid according to the method of 'Skraup) are hydrogenated at 140-180 C. in 300-400 parts by weight of water in the presence of a nickel catalyst with hydrogen under a pressure of 150Vatmospheres'. When hydrogen is no longer consumed the reaction mass is allowed to cool, the catalyst is separated, and the tetrahydronaphthopyridine sulfonic acid formed is precipitated by acidifying with hydrochloric 7 acid and is filtered. V V s V 100 parts by Weight of the tetrahydronaphthopyridine sulfonic acid are fused at 230-240? C. with 4 to 5 times-the quantity of potassiumhydroxide. After cooling, the melt isdissolved in Water and neutralized with hydrochloric: acid,

whereupon the py-tetrahydro-7-hydroxynaphthos pyridine probably of the formula: 1

separates in the form of practically colorless crystals; its hydrochloride is rather difficultly soluble in water and'crystallizes in the form of yellowish leaflets. 7

Example 2 16.8 parts by Weight of 5-nitro-2-anisidine are stirred into 40 parts by weight of concentrated hydrochloric acid and 40 parts by Weight of water;

whereby the chlorohydrate is formed. Now there is diazotized witha concentrated aqueous solution-of-BB parts by weight of'sodium nitrite,

small quantities of impurities are filtered off and the clear diazo solution is given into an aqueous solution of 23.5 parts by weight of py-tetrahydro- 7'7-hydroxynaphthopyridine chlorohydrate. After shortly stirring the couplin'g is complete; The

free mineral acid is neutralized with caustic soda lye andthedyestuff having the following formula: V. jv

r OH:

"NE" E:

on N=l I -N02 is isolated by summon. V The product when dyed on artificial acetate silk from a soap bath yields clearlight blue shades of good dischargeability.

Example 3 isisolated in the usual manner. It'dyes onjartificial acetate from a soap bath green shades of good fastness properties.

Acdyestufic of similar properties" is obtained by substituting the 2.4 -dinit1o6-brom0ani1ine by the 2.4-dinitro-6-chloroani1ine.

'Erampl e 4 15.4 parts by Weight of 5-nitro-2-aminophenol V are diazotized in a hydrochloric acid solution with an aqueous solution of 6.9 parts by weight of sodium nitrite. r The suspension of the diazo compound is poured into an aqueous solution of 23.5 parts by weight of pjr-tetrahydro-l-hydroxynaphthopyridine chlorohydrateQ After stirring for 12 hours the coupling is" complete, and the *dyestuff isolated having in its free state the following for mulaz r i CH2 is isolated by filtrationJ It gives, when dyed on acetate artificial silk in the usual manner, a clear "'greenish' blue of good dischargeability.

When coupling py-tetrahydro-l-ethyl-(or -l- ,hydrox'yethyl) '7 hydroxynaphthopyridine with in its free state the followfidiazotized p-nitraniline, there are obtained-dyeystuffs of the formulae: 1 5

oHl V on2 C2H5-N CH1 HooHlcH N" on, V

' CH: on,

respectively, dyeing cellulose acetate silk from a soap bath bluish-grey shades.

When coupling the same coupling components with diazotized 1-amino-2-chloro-4-nitrobenzene, there are obtained dyestuffs dyeing cellulose acetate silk bluish-green shades.

The py-tetrahydrol-ethyl-(or -1-hydroxyethyl-)7-hydroxynaphthopyridine are obtained. by reacting upon py-tetrahydro-7-naphthopyridine with ethyl chloride or chloroethyl alcohol, respectively, in the presence of chalk.

We claim:

1. Azodyestufis of the general formula:

wherein R stands for a member selected from the group consisting of an aromatic radical of the benzene and naphthalene series.

2. The dyestufi' of the following formula:

CH2 v IITOI dyeing cellulose acetate silk green shades. 3. The dyestufi of the general formula:

J OI-IANN HEINRICH HELBERGER. OTTO BAYER. 

